Induction heat treating apparatus



April 28, 1942.

H. E. SOMES 2,281,331

INDUCTION HEAT TREATING APPARATUS Filed Sept. 17, 1937 9 Sheets-Sheet l y r i I I INVENTOR. .139

fiowm'dfi'l 5017285 144.- 129 i 29 153 127 27 I 127's 127 ATTORNEY.

A ril 28, 1942. H. E. SOMES 2,231,331

INDUCTION HEAT TREATING APPARATUS Filed Sept. 17, 1957 9 Sheets-Sheet 2 H. E. SOMES 2,281,331

INDUCTION HEAT TREATING APPARATUS Filed Sept. 17, 1937 April 28, 1942.

9 Sheets-Sheet 3 13 fig 5,

2 INVENTOR.

ATTORNEY.

A'pril 28, 1942. H. SOMES 2,281,331

INDUCTION HEAT TREATING APPARATUS Filed Sept. 17, 1937 9 She ets-She et 5 m 53 R INVENTOR.

flowardfi, Games WWW ATTORNEY.

April 28, 1942.

H. a. SOMES INDUCTION HEAT TREATING APPARATUS Filed Sept. 17, 1937 9 Sheets-Sheet 6 INVENTOR.

ATTORNEY.

April 1942- a. E. soMEs 2,281,331

INDUCTION HEAT TREATING APPARATUS FiledSept. 17; 1957 9 Sheets-Sheet 8 ii/bwardli'. Jam/es ATTORNEY.

Patented Apr. 28, 1942 INDUCTION HilA'If TREATING APPARATUS Howard E. Somes, Detroit, Mich, assignor to Budd Induction Haul, 1110-, Philadelphia, Pa., a corporationof Michigan Application September 17, 1937, Serial No. 164,320

29 Claims- The present invention relates in general to apparatus for the heat treatment of objects by electro-magnetic induction and in particular to apparatus and method for the heat treatment of annular-form objects by high frequency electromagnetic induction.

The invention in great part relates to improvements in the art to which pertain my co-pending applications Serial No. 96,346, filed August 17, 1936'; and Serial Number 121,598, filed January 21, 1937, now Patent No. 2,208,607 issued July 23, 1940.

An important object'of the invention isthe provision of an apparatus adapted for effecting the heat treatment of objects of various forms and sizes, and in various ways with substantially no variation in the apparatus structure other than the tool or heating element, for adaptation to such different forms or for the application of different kinds of treatment.

Another object of the invention is the provision of apparatus of universal application as mentioned, but compact in form and readily adjustable or alterable, both mechanically and electrically to its different uses formaximum efliciency for each such use.

Another object is' the provision of apparatus enabling the attainment of extreme uniformity in the application ofheating energy particularly as to rate of input and the total amount of energy applied throughout an annular zone. heretofor unattainable in low turn stationary inducing coils because:- coils having eachturn a complete unit turn of 360 could not be built due to the necessity for-current leads'and their insulation, and because the presence of the necessary leads, in the case of an internal coil seriously interfere with the uniform distribution of magnetic flux.

Another object ancillary to the above is the provision of means enabling relative rotary movement between the inducing coil and the work piece without complication of the means for continuously supplying energy and cooling fluid to the coil and with substantially no variation in the electrical constants of the work circuit.,-

Various other objects and advantagesof the invention will appear from aperusal of the following specificationand 'thedrawi'ngs accompanying the same.

In the drawings: 7 v Fig. 1 is a side elevation of my improved apparatus. i

Fig. 2 is a front elevation ing from the right of Fig. 1.

Fig. 3 is a horizontal cross section on the line 3-3 of Fig. 2and on an enlarge scale.

,Fig. 4 is a slightly enlarged sectional view on.

the line 4-4 of Fig. 2.

or me same look- Fig. 5 is an enlarged view partly in section on theline s 5 of Fig. 2 showing the switching transformer in uncoupled position.

. Fig. 6 is a cross sectional view taken on the line 55 of Fig. 2 showing the switching trans-,

former in coupled position.

Fig. 7 is an axial section through the induction head taken on the line |I of F18. 1, and

on an enlarged scale. a

Fig; 8 is an enlarged front elevationp partly in axial section, showingthe'work holding portion of the machine. 1

Fig. 9 is a-side view'in axial section of the work platform and work holder looking from the left of Fig. -2.

Fig. 10 is a top plan view partly in section to Figs. 1 to 4, the apparatus consists in genply line 29.

eral of a switching transformer element l0 comprised of a stationary casing H in which is slidably mounted a primary element support l2 carrying a primary transformer. element movable into and out of transformer coupling rela-' tion with a secondary element contained withinthe casing II. The primary element support It is carried for such sliding movement by the ho].- low primary element carrier shaft I! which is moved up anddown by means of a suitable motor cylinder l4.

Tool shaft 15 extends through the hollow carrier shaft [3 and through the center of the switching transformer I0, and at its lower end carries the induction head IS. The tool shaft I5 is arranged for both sliding and rotary motion, the sliding motion being imparted by means of the motor cylinder I1 and the rotary motion by means of a gear [8 and elongated pinion l8 driven by an electric motor 20.

At the lower part of the apparatus assembly is mounted an adjustable work carriage 2| carrying a vertical movable work holder 22 for holding the work piece in operative position rel ative to the induction head i6;

Cooling and quenching-fluid is supplied to the induction head l6 and a quench nozzle 24 at the bottom of the head, through the tool shaft l5 which is'made tubular for this purpose, and to which fluid is suppliedthrough the upp r tubular extension 25 arranged to receive fluid through a slide union 26 into which cooling and quenching fluid is supplied through the pipe and the control valve 28 from a suitable sup Current is supplidto the primary of the transformer through suitable leads II. A pair of multiple leads 3l3-i connect the terminals of the transformer secondary winding t0 a group'of capacitors 32 for power factor correction. The various main-elements'above menformer casing H i the casing is provided with a tioned are held in-proper operative relation as shown by means of a suitable substantiallyrigid and strong framework 32'.

The switching transformer i is mounted on the main frame by means of the transformer casing II in the form of a bracket supported ring or short cylinder casing secured to the front plate element of the frame by means of the wing flanges 33 and the bolts 34. It is thus held stationary with respect to the frame. As shown more in detail in Figs. and 6, the transformer casing ll carries a bottom mounting ring'I-'" -bolted"to the lower end flangeof the casing it 36 ,which mounting ring in turn carries a tubular secondary core support 31 bolted to .the mounting ring-35 at 38; Near its center the secondary-coresupport 31 carries an intermediateclamping flange I) between which and a top clamping ring 40 are clamped an annular series of radial laminations 4| forming the magguide slot 5| with which engages a guide stud 58 carried by'the sliding. primary. element. This slot '8 also affords an elongated opening for entrance of the terminals 58 through the casing to the primary element. The transformer primary element 46 is thus capable of sliding free-- ly from the lowered position shown in Fig. 5 t

its raised position'shown in Fig. 6. v

Slidably mounted within the hollow of the tubular secondary core support II'is-a hollow .tool shaft I! which has bearing at the'bottom of the transformercasing in a bearing support netic core of the transformer secondary eleg mounting ring 35.

ment 42. The radial laminations are preferably tapered as by grinding or other suitable process to form in effect a solid mass of laminated material: Within an outer recessed portion 43 of the core element thus formed'by the laminations 4i is mounted the secondary winding 44 ofthe transformer consisting of a four-stranded tubular conductor as shown. Below .thelaminati'ons 4| the core support 31 carries an auxiliary 60 through an intervening conductor sleeve Cl surrounding the tool .shaft but insulated therefrom by a sleeve 82 of insulating material. The conductor sleeve 6| has bearing in the bushing 63 which is mounted in the support 60 through the intermediation of an insulating bushing 64, V

Bolts 65 secure the support" to the bottom mounting ring 35. shaft l5 carries the induction head it as an enlarged portion thereof comprising an innertubular extension I! and an outer cylindrical 1 extension 61. The outer tubular extension carries" an annular series of taper-ground radial laminations 68 clamped in place between the bottom core element 45, also built up of taper-ground radiallamin'ations clamped in place between the intermediate clamping flange 39 and the bottom 'The primary transformer element 46 surrounding the secondary element 42 is mounted in I a"' cylindrical primary element casing 41 carried by the primary element support i2 and arranged to slide in bearing contact with the stationary transformer casing H i r The primary transformer element 4 is comprised of an annular series .of' taper-ground radial laminations 40' forming an annular core element in an inner annular recessed portion 49 of which is mounted the primary winding 50 ofthetra'nsformer formed :of the usual hollow tubular conductor. The laminations 48 are clamped in place within the casing '41 between the top flange Bi and the.

bottom clamping ring 52 clamped onto the lowerend of the casing" bysuitable bolts 53.

a Current is led. to the primary winding 50 by flange 68' on the cylindrical extension 01 and a top clamping ring 10 held down against the laminations by clamping ring-nut Ii threaded onto the'outer cylindrical extension 61. Within an outer annular recess 12 in the ring of laminations 88 is mountedan inducting coil or work coil ll formed from a tubular conductor. One terminal 14 of the coil" is electrically connected through an inwardly extending tubular The lower end'of the-tool member 15 with the inner extension "through the metallic terminal ring/16 through which the tubular extension I! extends in a water tight connection to the inner opening of the inner extension 86, the terminal ring ll-being secured to the end of the extension by means of suitable bolts The other terminal ll of the in-.

- ducing coil is electrically connected through the coupling elements IO-l0 and conducting "'rod II to the conductor sleeve 6i, the conductor rod 0i making contact with the sleeve through v the flange '2 into which it enters and with which means of the terminal elements 54, extending.

outwardly through a radially tapered block 55 of insulating materialinserted between the, core laminations, theterminal elements. 44 connecting outside of the block with outside terminal elements it secured to the block through bolts The'outside terminals 56 are made in the form of electrical and fluid coupling elements for connection with suitable flexible water cooled current leads It connected with a suitable source of high frequency current supply and cooling fluid. The block 55 of insulating material is made in the form of a tapering wedge sufficiently thick to surround the terminal elements .54 "and insulate them from the laminations, the insulating block 55 beingclamped in place between the laminations in the same manner as the lami' nations are clamped, that is between the upper flange SI of the casing 41 and the lower clamping ring 5 2, as is clearly shown at the left of Figs.;5 and 6. To prevent turning movement of the primary element with respect to the transit may be secured in any'suitable manner as by brazing orin any othersuitable manner. Fluid connection between the terminal 18 and fluid chamber 83 is afforded by meansof an opening 84 formed in the coupling element 18' and arranged to have communication with the opening in the conductor terminal fl! and the liquid chamber '3.

Thus the tool mm II and, consumerism n 1 form conductor leads extending from the work coil ll up into the tubular secondary coil s1 pport 31 for electrical connection with the terminals of the transformer secondary-winding 44. Such connection is effected througha pair I of annular-form brushes" and It arranged bear against the tool shaft i5 and conductor-- sleeve lirespecti'vely. Each of these brushes,

for example, 85, has an upper base portion II in the form of a solid ring carrying an integral downwardly extending, thin walled cylindrical portion 08 slotted longitudinally from the bottom edge to the base at close intervals to'form a plurality of downwardly extending narrow resil-' ientflngers to press against the tool shaft. 1 To enhance this resiliency, the brush elements are formed of suitable resilient conducting material such as beryllium copper. The upper brush .6

is secured to the inner wall of the secondary coil support 31 by means of its upper base portion II which is threaded into the inner wall of the tubular support 31. The tubular support being of conducting material, preferably a bronze casting, makes good electrical contact with the brush element through its threaded connection therewith and continues this connection to the upper terminal block I! of the secondary coil which terminal, as shown in Fig. 6, is formed as an integral lug extending radially outwardly from the support 31 through the radially tapered block I of insulating material and into electrical contact with the upper terminal of the four-stranded conductor of the secondary coil. The lower brush element 86 is mounted within the tubular sup-v port 31 between a pair of cylindrical clamping elements Qi and I! of conducting material, the

' outer conducting element It extending upwardly to near the lower end of the secondary coil where it is secured in electrical contact with a solid ring element ll of conducting material by threaded engagement therewith, the ring element as being insulated from the tubular support element 31 by an annular bushing 04 of insulating material seated in an annular shouldered portion of the tubular support 31. The

ment of 'both fluid connection therewith.. To effect this connection the flexible tubes 3| jl'ofconducting material are connected through electrical and fluid, conducting 7 angle joints III and ill to conductingtubes I and I respectively which extend-down into electrical and fluid connection with theterminalsof the four-stranded'conductor of thesec ondary winding through the blocks."

and II, the conductor tube 'll llleading to the insulated terminal block II beinginsulated from the support element 81 by means of an outer insuiating tube I". The multipleleads 3|, ii are electrically connected with a bank of capacitors and are mechanically connected to suitable insulating tubing which has rubber hose to a suitable source of cooling fluid such as water, which connections and source are not here shown, it bering member 93, thus insulated from the support .of the terminal plug 95 soas to surround the same and insulate it from the lamlnations. Where the plug 95 passes through the wall of the support element 31, it is insulated therefrom at the bottom by an insulating spacer element It,

ing understood that such may be established in any manner known in the art.

For indicating the volume of current flowing in the secondary circuit through the brush elements ll, 80 a current-ratio transformer I is provided in the form of a 'toroid extending around the outer circumference of the upper brush element ll so that the current passing from theterminals of thesecondary through the brush elements will loop through and around the toroid. By so placing the current transformer, its magnetic and electrical circuits are I positioned at right angles to the electrical and the opening through the tubular support 31 being sufllciently high to afford air insulation between the plug and the support I! as indicated at 1. Similarly, the sides of the terminal block I! may be air insulated from the support "by suitable spacing or may be separated by solid spacing members of insulating material as will be well understood by those skilled in the art.

The clamping elements II and 02 are thus held flrmly clamped in position together with the magnetic circuits, respectively, of the primary coil, thus rendering it substantially uninfluenced by current in the primary coil. The current transformer I It is connected through a pair of leads I" extending out through the slot opening ill in the primary element support If, to a suitable indicating instrument not shown.

The electrical circuit connection between the work coil 13 and the transformer secondary wind-- ing 44 may be traced from: grounded secondary terminal block ll, support element 81, base, ring '1 of brush II, brush ll, tool shaft ll, inner extension 88 of induction head I, terminal extension ll of the lower grounded terminal ll of work coil 13, through work coil ll, upper insulated terminal II of the work coil, insulated terminal connections II and II, insulated conmetallic bushing 88 through said insulating bushings by means of the lower bearing support I! clamped onto the bottom mounting ring ll by bolts II. By vertically spacing the brushes II and 80 and having the conducting sleeve lie:-

tend upwardly to near the top brush when in the raised position as shown in Fig. 6, the tool shaft II and conductor sleeve I are enabled to be slid vertically for a distance substantially equal to such spacing while maintaining proper contact with the elements. Similarly, the tool shaft together with the conducting sleeve Bl may be rotated without affecting the continuous contact of the brushes with the shaft and conductor sleeve.

The multiple leads ll,,ll"'ail'ord a multiple connection from the terminals of'the secondary coil to the bank of capacitors 32 for power factor correction of the secondary circuit, as well as means for supplying cooling fluid to the secondary coil. This double function is obtained in general in the usual manner by providing such necting bolt ll, insulated conductor sleevell, to lower brush element It, and thence to conductor extension I! and insulated terminal block ll, back to the secondary winding through the lower insulated terminal of the winding.

Motion is imparted to the transformer primary element 0 to move it from the lower uncoupled position shownin Fig. 5 to the upper'coupled position shown in Fig. 6, and vice versa, through theprimary element support if and its hollow carrier shaft 18 by the piston I (Fig. 4) of the fluid motor I, to which piston the carrier shaft is is flxed. Movement of the piston I" is effect-- ed by admission and release of air or other working fluid into and from the work cylinder ll at opposite sides of the piston through a suitable slide valve Ill controlled in known manner by an electro-magnetically actuated control .valve I" (Fig. 2); As various types of such controls are well-known in-the art, it is deemed unnecessary to describe the same in detail. Suflice it to say that the: controls are so arranged that normally the piston IN is in the lower position and upon 'energization of the electro-magnetic control valve Ill, is raised to the top position and held leads in the form of hollow conductors properly 7 there during such energization, and upon d connected to the coil terminals for 'establish- 2,2'e1,as"1"" and 'the onetime ,element 2 3 's,; t at 1am- I.

energization oLthe control is returned to the lower position;v Vertical sliding movement of the tool-shaft through the switching trans- A former and the 'hollowgcarrier shaft n is er ted. by-the work piston [09 in work. cylinder H, to.

which piston the tool shaft !5, is attachedforj sliding movement therewith, The work \piston "Sis operated .by'admission and release of air orotherworklng fluid-toopposite sides of the;

piston in known manner as described in connectiowwith the operation of the work cylinder ll,

the'operation of the cylinder l'l being controlled. 1

through the slide valve HI! and electro-magneti;

cally actuated control valve!!! (Fig. .Zlin a manner "such that normally the piston. ID! will remainin the lowermost position and upon ener gization of itscontrolling electro-magnetic valve;

II! will be raised to the upper-most position and held there during such energization and upon;

de-energization of the control, valve willbe returned to thelowermost position. Rotary motion is impartedtothe shaft l5, ,independentlyiofits 7 vertical movement, through the gear it fixed to the upperendxof the shaft. !5, and'elongated; pinion I 5, from a suitablezelectric. motor 20.;

upper -extension.25 .in' the form of a tube closed hollow tool carrier shaft ii for conductiongob quenching fluid to the .hollow shaft-i5 iuninter v rupted by the sliding and rotary motion. thereof,

to which end the tubular extension extends up- 'wa'rdly into a slide union 26 inthe form ofra v cylindrical chamberwelement .in which the tubu-.

lar extension 254s arranged to slide and rotate through fluiditightstuflingboxes!l2, H3. The interior 'of the tubular. extension 2ixcornmunithe intermediateelement 24 I sf clamped in pe il. tion through "a ser e or clamping bolts-T24. n is to be notedthat thejsurfaces of the spray slots l2! and 12'! are inclined downwardly with-re spectto the horizontal infa'direction'away from they direction "of movement of the heating head and that'as a result of such inclination 5 the quenching fluidwill not react or reflect from the surface being quenched to contact the*inducing'-- coilpr the immediate surfacebeing heated. I Below the induction head It an adiustable work platform 2! is slldabl mounted on a-pair of uprights! forming part of the mainframe structure 32", and is arranged to be moved up and down by a pair ,of elevating screws I26 driven through a setof .bevel gears l2! and transmission shafts I28 from the stub shaft 129 square ended for-engagement by a suitable operating crank not shown. Asshown morein detail in Fig. 8, the

work" platform 2! "carries a vertically movable workiholder 22 mountedvfor vertical movement ,onthe platform by means of a set of three guide rods Hlslidablymounted in the tubular guide members l3! and the platform 2! The work holder 22 connects with guide rods l3!) for movement thereby .through short studs I32 on the upper end of the rodswhich engage-through openings- I33 in the work ;holder '22 thus jen ablingvarious interchangeable work-holders -provided wi th,l ile arrangements of openings I33 to cates with the interior of the slide. union 21 through an'opening- I l4, and cooling and quenching fluid is-supplied to the interiorof the union 28 through theconduit: 2'! (Fig. .2), electro magnetically controlled. valve 28 and conduit 2! from a suitable source of .such fluid under pressure not shown. 1 I

The cooling and quenching: fluid ,supplied through union 26 (Fig. 4) and controlled-in its fi'ow'by valve 28 (Fig.2) is conducted on ;down through the extension 2 5 and. hollowxtube shaft IE to the induction head l6 and nozzle 2,l-:(Fig.- The cooling fluid-passingzinto-thetubular- 7).. channelthrough the inner extension 66 v of the induction .head- (Fig. .7), is conducted through,

be used inplacepf the work' holder (where required. The three slide rods Hill are connected at their bottom ends for movement as a unit by a yoke member 134. The yoke I34 is ar-' ranged tobe raised and lowered by a work cylinder I35 mounted in the lower part of the well 136 forminga. part ofthe work platform; The work cylinder is provided; withwork piston 131 which the lower positionfsliown (Figs; 8 and9) up into" the channel in, the terminal extension 15 to the lower terminal I4 of the work coil-and thence throughthe work coil'and out through theupper terminal 18 and lower opening in the coupling element into theannular. chamber 83. in the From the chamber the cooling fluid exhausts throughan annular seriesof eX-w nozzle cap 24-.

haust openings I IS in the nozzle .cap 24. 1 For quenching, the coolingand; quenching fluid; moving on downthrough the inner channel in the inner extension. 66.130 the. central chamber lfl 'in the nozzle cap, is distributed radially.

therefrom through radially, extending channels I8 to the upper and lowerlannular passages I9.

carries the tubular.shaft"l38 connectedat its lower end to thel' lower endofa centralating iluidcpnnection with the top and bottom of the work. cylinder is had through suitable pipe connections l lfl, I (Fig. 9) leading fromsuit able fluidcontrol mechanism'not'shown;

Mounted -centrally of the work carriage and extending through the work cylinder I35 oiap plication tbthefwork, is a bottom, movable spray nozzle element 2 arranged to be moved from operating position with relation to the work bymeans of .an "elongated work,,, cylinder I43 extending down through" the" workicylinder I35 and hollow shaft I33 through and' below the yoke offset I38 where it ,terminates'inja bottom cylinder, head. This elongated work cylinder isprovided with a'work piston I45 which carries the movable nozzletube I4 6 normally held in its lowermost position by meansfof a compression 7 spring HIjbearingj at its lower endagainst'the and 120 and out through the radial spray slots !2! and I22 respectively, from whichthe fluid is forced downwardly and outwardly from below flange 89 toimpinge againstthe heated-portion of the Work being treated: which portion, in the present showing, isv the inner surface of the hub-of a-cariwheelhere shown as. the workpiece 23. The width of; the.:annular.-slots l2 m gphe piston us and at'its an inner shouldered portion I58 inthe wall of the elongated work-cylinder. Oper'ating-J-fluid is supplied to the'bottom end ofthe work cylinderv Hlthrough supply pipe "!39(Fig. 8) and-inlet upper-end against ducts H9 in the cylinder head I, which -operating fluid is also used asthe quenching fluid for the nozzle [42. To permit entrance of fiuid to and H115 determinedand fixed byproperdimensioning of the intermediate nozzle member 24' the nozzle tube l46'only during-elevated position of the nozzle 2, a stationary sleeve valve I50 (Fig.5 9) having valve openings !5! normally closed by the walls of nozzle tube 1463s mount ed on! a valve stem I52 extendingdownwardly through the nozzle tube and secured at the-bob I downwardly extendingyoke offset'portion I39. Opertom of the cylinder head iii through a threaded and capped end portion I. As will be clear from the drawings especially Fig. 9, communication Between the interior of the sleeve valve I50 and the piston chamber I64 will be efiected upon movement of the piston I45 into its uppermost position in abutment with the shoulder I55, by movement of the bottom end of the piston upwardly beyond the valve openings I51. The waste quench fluid from the nozzle I42 as well as from the quenching nozzle 24 on the induction head I6 collects in the platform well I36 from whence it is drained oif through drai pipe I66 (Fig. 8).

The cylindrical work piece 23 here shown as a car wheel is mounted on the work holder 22 through the intermediation of a bottom endring I51, the work being capped by a top endring I50. The purpose of the end rings is to provide a temporary continuation of the work piece beyond the portions to be treated to avoid undesirable electro-magnetic end effects at the ends of the actual work-piece. For this purpose, the end-rings are perfectly formed of a material substantially the electro-magnetic equivalent of the material of the work-piece.

n relatively large work such as the workpiece 23 here shown, where an induction head of the type I6 effects the treatment by upward movement through the work-piece during energization, the quenching nozzle 24 carried by the induction head is ordinarily relied upon for effecting the quenching at the proper temperature, the lower movable quenching nozzle I42 being used mainly for smaller work such as automobile wheel hubs and small engine cylinders, although, on occasion, where desirable both types of quenching nozzles may be used on the one work-piece, for example the nozzle 24 carried by the induction head I6 may be used for bringing the work-piece to the desired quenching temperature progressively upwardly with the upward movement of the induction head, after which further cooling of the work may be e1- fected through use of the bottom quenching nozzle I42.

An important detail feature of the various work cylinders is the arrangement for cushioning the end stroke of'the piston. As such arrangement is substantially the same for the various work cylinders, it will suiiice to refer in detail to one, for example the work cylinder I4 (Fig. 4). Here it will be seen that the bottom cylinder head I56 is provided with a cylindrical passage I60 about the carrier shaft I3 through which the work cylinder chamber communicates with the inlet-outlet duct I6I in the cylinder head, which cylindrical passage I60 is arranged to be closed by the enlarged portion I62 of the carrier shaft I3 during the latter or end portion of the downward stroke of the piston, thereby cutting off the exit of working fluid from the cylinder chamber through the opening I60 and confining its exit to the duct I6I by way of by-pass channel I00 controlled by a needle valve I63. Thus by suitable adjustment of the needle valve I63, the rate of exhaust of working fluid from the cylinder at the end of the stroke may be adjusted to give any desired cushioning efiect. The upper end of the work cylinder is constructed similarly to that of the lower end for effecting a regulated cushioning at the end of the up stroke. Here also a needle valve and by-pass duct, not shown, is provided for controlling communication between the opening I64 and the Inlet-outlet channel III.

In operation, assuming the work platform 2I to be adjusted to the position shown in Figs. 1 and 2 for operating on the car wheel 23, the work holder in the lower position as shown in Figs. 1, 2 and 7, the induction head in the upper position as shown in Figs. 1 and 2, and the primary element of the switching transformer in the lower uncoupled position as shown in Fig. 5, the operator positions the work-piece 23 on the work holder with the, end-rings 51-50 in position as shown in Figs. 1, 2 and 7. Working fluid is now let into the bottom of the elevating cylinder I06 (Figs. 8 and 9) through the pipe I H and suitable control means not shown to elevate the work holder 22 and work-piece 23 up into a position shown in dotted lines in Fig. 8. While the workpiece is held in this elevated position, electromagnetic valve III (Figs. 1 and 2) is actuated to eifect admission of working fluid to the top of cylinder I! which moving downwardly moves the tool shaft I5 and induction head It downwardly into andthrough the hub of the car wheel 23 to the position shown in dotted linesin Fig. 8 slightly below the lower edge of thehub but within the lower end-ring I 51 which has been raised with the work. This puts the heat treating head I6 in the starting position. Electromagnetic valve I00, Fig. 2, is now operated to admit working fluid under pressure to the lower end of work cylinder I4 to quickly raise the primary element support I2 and with it the transformer primary element 46 (Figs. 5 and 6) from the uncoupled position shown in Fig. 5 to the coupled position shown in Fig. 6, whereupon the secondary winding 24 becomes energized, delivering current through the conductor extensions formed by the tool shaft I5 and conducting sleeve 6| to the work coil 13 (Figs. 5 and 7) as heretofore described. The work coil 13 being now energized induces a heating current in the lower ring element I5I. Substantially at the same instant. electromagnetic valve 26 is actuated admitting cooling and quenching fluid through the slide union 26 and on down through the tubular work shaft I5 to the induction head I6. The quenching fluid passing partly through the work coil to cool the same, thence out through the bottom of the induction head, and partly through the slot openings in the nozzle head 24 to impinge against the surrounding surface of the bottom end-ring element I51. Also at substantially the same instant the induction head I6 is started on an upward movement and the work holder with the work-piece 23 started on the downward movement at predetermined rates so as to move the work-piece with its end-rings and the induction head from the position shown in dotted lines in Fig. 8 to the position shown in solid lines in Fig. 8. Upward movement of the induction head I6 at predetermined rate is effected by actuation of the electromagnetic valve III of the work cylinder I'I (Figs. 1, 2 and 4) to release working fluid from the top of theworking cylinder I1 and admit working fluid to the bottom of the cylinder at a predetermined constant rate of flow which may be regulated by the needle valve I66 (Fig. 2) or other suitable means.

ulated downward movement of the work is ei' fected by suitable regulated control of the flow of working fluid out of the bottom and into the top of the work cylinder I35 through pipes HI and I40. To assure accuracy in control a noncompressible operating fluid may be used, hav- Similarly, reg

ing its rate of flow positively controlled as by a gear pump or other suitable flow control means.

flower end-ring I51 through the inner cylindrical wall portion of the work-piece to the top endring I58, followed immediately by the coolin eflfect of the quenching spray delivered from the quenching nozzle 24, to effect uniform heat treatment of the work-piece throughout an interior annular zone as indicated at I61 by the heavy hatching in Fig. 7.

When the induction head reaches a position Just ready to emerge from the top end-ring I58, the work coil I3 is immediately de-energized by deenergization oi electro-magnetic valve I08 (Fig. 2) to release working fluid from the bottom of work cylinder I4 and admit working fluid to the top thereof, to effect movement of the transformer primary element 46 (Figs. 5 and 6) from the upper'position of Fig. 6 back to the lower uncoupled position of Fig. 5 thus de-energizing the secondary winding. It will be noted that this switching of! of the current is effected without undue change in the electrical characteristics of the primary circuit due to substitution of the auxiliary laminated core'element 45 for the core element of the secondary winding, in a manner and through the use of a structure similar to that disclosed in my co-pending application Serial N0. 96,929, filed August 20, 1936. The induction head and work piece continue their relative movement until both spray slots I2I and I22 are above the upper edge of the work piece 23 and still within the upper end-ring I58 whereupon they pause in their relative movement to permit the quenching spray to continue to wash the entire inner wall of the work piece for a determinate time sufficient to insure complete quenching of the upper portions' Thereafter the electromagnetic valve element 28 (Fig. 2) is actuated to shut off the cooling and quenching fluid. The induction head and work piece 23 then continue their relative movement to bring them into the position shown in solid lines in Fig. 8 which is the same as the load and unload position shown in Figs. 1 and 2, after which the work-piece 23 may be removed, substituted by an untreated work-piece and the operation repeated as above described.

In the operation above described, after the induction head is de-energized, the necessity for accurately timed relative movement between the induction head and the work piece no longer exists so that these two parts may be moved either at the same'or different times and at any speed convenient to the carrying out of the remainder of the operation. For example, after de-energization of the induction head, either the induction head or the work piece, or both may be rapidly moved to position the spray slots above the upper end of the work piece within the upper end-ring I58, and after the pause for additional quenching the parts may be rapidly moved away from each other into the unload shown in solid lines in Fig. 8.

In the operation above described it is to be understood, of course, that the quenching and cooling fluid will be supplied at such volume and pressure that the back pressure built up in the chamber I I1 due to the restricted flow through the continuously open annular nozzle passages position I2I and I22 will be suflicient to force the cooling fluid through the coil I3 from the trailing terminal thereof to the leading terminal in the direction of progressive movement of the heating head through the workpiece.

It is to .be noted that by arranging the nozzle passage I2I at the under side of the abutment flange for the core 88 an annular jet or sheet of cooling fluid will issue substantially directly. from the lower edge of the flange 69 with the resuit that the zone of the initial contact of the quenching fluid with the workpiece is brought into extremely close proximity to the trailing end of the heated zone which is the hottest portion of the heated zone due to its relatively longer exposure to the heating influence of the heat treating head. It is to be noted further that an advantage of the arrangement whereby the cooling fluid is directed through the hollow conductor of the coil 13 from the bottom to the top, that is, in the direction of travel of the coil I3 relative to the workpiece, is that that part or the coil which is presented to the hottest portion of the progressing heated zone is the first to receive the cooling fluid. Also, because the coil is intended to travel upwardly through the workpiece with the result that it is the lowest terminal of the coil which is presented to the hottest part of the heated zone, this is the one selected for connection with the mandrel I5 whereby that portion of the coil is maintained at substantially the same potential as the workpiece.

It Is desirable at times to rotate the work piece during treatment thereof and to this end I provide the rotatable work holder I10 (Figs. 10 to 13) mounted in a casing III adapted to be positioned on the work holder carriage posts IIII. The work holder I'III is annular in form and has rotatable bearing in the casing "I through a V-shaped bearing ring I" carried by the holder slidable in the complementary annular V-shaped trough I13 formed in the casing. The rotation of the holder I" is effected by means of a wormgear ring I14 and worm I15 driven through bevel gears I" by an electric motor I". The motor I" is mounted by means of a bracket extension I'll carried by the casing III. A coverring I94 secured to the casing in by screws I95 (Fig. 10) guards the work holder against upward displacement and shields the driving mechanism from the quenching fluid. The work piece I19 which in the present instance is an automobile wheel hub, is held centered in position in the work holder through the intermediation of a ring shaped adaptor element I80 fastened to the holder I'll by suitable cap screws I8l. To insure a positive holding of the work in fixed relation to the movable work holder III! a pair of chucking jaws I82 are mounted on the bottom of the work holder and. arranged to be moved into engagement with the lower end of the work piece by means of the fluid operated work cylinders I. The chucking jaws I82 are each arranged to be operated by its work cylinder I83 through a piston rod I carried at the end of a hollow cylindrical piston element I85 normally held by a compression spring I85 in its radially innermost position to normally hold the chucking jaws I83 in clamping position under spring tension, fluid under pressure being admitted to the forward side of the piston through supply pipe I81 to retract the chucking jaws into open position for placement and withdrawal of the work. In the present instance the chucking jaws are shaped and arranged to engage the work piece through the annular hub-puller recess normally provided in such work piece.

Also mounted at the bottom of the casing III on opposite sides of the central opening are a pair of control switches I99 and I09 operated by levers I90 and I9I respectively positioned to be actuated by engagement; of the lower end of the work piece I19 therewith. The purpose of these switches is to control suitable safety control circuits not shown which do not form an essential part of the present invention and which may form part of a sequence control system for the machine similar to that shown in my copending application Serial No. 96,346, filed August 17, 1936. Suffice it to say here that the switches I88 and I89 are of a type which are normally open and are adapted to be closed upon upward movement of their operating plungers I92. Thus, as shown in Fig. 12, the switch Ill is shown with its plunger I92 held up by the lever I90 to maintain the switch in closed position, while the switch I99 is shown with its plunger released by downward movement of the lever I9I to maintain the switch in open position, the levers I90 and I9I being so held by engagement of the lower end of the work therewith. Thus with the work piece in place the switch I89 is held closed while the switch I99 is held open. Immediately upon removal of the work piece the levers I90 and I9I are permitted to move upwardly to open the switch I" and close the switch I89. Upward movement of the lever I9I with sufilcient force to actuate the switch I99 is effected by means of a suitable compression spring I99 while the retractile spring normally provided as part of the switch I08, but not here shown, is relied upon to raise the lever I90 through downward movement of the switch plunger I92 by such retractilespring.

Where the work holder I10 is used in place of the work holder 22 of Fig. 8 and to adapt the machine for operation on smaller work such as the hub I19 (Fig. 12), the induction head It of Figs. 1 to 8 is replaced by the smaller induction head I6 of Fig. 12 suitably designed for operative engagement with the work piece I19 and carried at the end of a sleeve conductor 9| and tool shaft I replacing the sleeve conductor BI and tool shaft 15 of Figs. 1 to 8.

With the use of the rotatable work holder I10 shown in Figs. 10 to 13 the work piece I19 may be raised and lowered into and out of operative relation with the induction head I0 as well as rotated relative thereto, without movement of the induction head, which is convenient and preferable where operating on small work pieces such as the automobile wheel hub I19. Also, where it is desired to attain high relative rotational movement between the work piece and the induction head both such elements may be rotated in opposite directions thus avoiding any such undue vibration as would occur under the same relative rotational velocity attained by movement of one of the elements alone.

In operating on smaller work pieces such as the wheel hub I19 it is preferable to eil'ect a sudden quenching of the entire treated surface at one time which is most conveniently attained through use of the bottom quenching nozzle I42 which in Fig. 12 is shown in the uppermost or active quenching position. It is in such position that the quenching fluid will be supplied to the nozzle through the valve openings IlI, Fig. 9, as described in connection with Figs. 8 and 9.

It is further to be pointed out that with the frame, and 'an induction heating element carried improved form of heating coll shown in Fig. 7 in which the axial extent is extremely short compared with the diameter so that the magnetic circuit is restricted in axial extent to several times less than the diameter, the depth of the high density magnetic flux and consequently the depth of the treated zone may be kept small, and this regardless of the size of the work piece.

What I claim is: Y

1. Apparatus for heat treating a work piece by electro-magnetic induction comprising a stationary support, a work holder for holding the work piece, a tool shaft slidably mounted on said support and having a channel therein, an induction head carried by said shaft for movement with the shaft into and out of operative heating relation with the work piece held in said work holder, a tubular heating coil carried by said induction head, and a quenching nozzle carried by the induction head having fluid connection with the channel in said tool shaft, one terminal of said tubular coil communicating with the channel in said shaft and the other terminal communicating with a space beyond the nozzle on the side away from the induction head.

2. Apparatus for heat treating a portion of a work piece by electro-magnetic induction comprising a supporting frame, a work supportslidably mounted on said frame, means for holdin a work piece on said support, an induction head slidably mounted on said supporting frame for movement into and out of operative heating relation with the work piece held by said holding means, a spray nozzle mounted on said work support independently of said frame and arranged for movement into and out of spraying relation with work piece held by said holder, and motor means mounted on said work supportindependently of said frame for moving said nozzle into and out of spraying relation with the work piece.

3. Apparatus for heat treating a work piece by electro-magnetic induction comprising a supporting frame, a work cylinder mounted on the frame, a work piston in said cylinder, a tool shaft connected to the piston for operation thereby as a piston rod, a work holder, an induction head carried by the shaft for movement into and out of operative relation with a work piece held by said work holder, a main inlet-outlet conduit communicating with the interior of said work cylinder for admission and release of working fluid to and from the interior of the cylinder, means movable with the piston to close off communication between the said conduit and the exhaust end of the cylinder near the end of a piston stroke, and a by-pass conduit permanently connecting said inlet-outlet conduit with said exhaust end of the cylinder independently of said means movable with the piston. a,

4. Apparatus for heat treating a work piece by electro-magnetic induction comprising a stationary supporting frame, a work holder casing mounted on said supporting frame, a work holder rotatably mounted in said casing, motor means mounted on said casingfor rotating said work holder, 8. tool shaft slidably mounted on said by said shaft for movement into and out of operative relation with a work piece held by said holder independently of the rotary motion of the work piece by said holder.

5. Apparatus for heat treating a work piece by electro-magnetic induction comprising a transformer having a secondary winding and a hollow core therefor, a tool shaft extending through said core and being movable relative thereto, an induction heating coil carried by said tool shaft for movement therewith relative to the work piece, a circuit conductor element carried by said tool shaft, said conductor element and said tool shaft being insulated from each other and connected to the terminals of said coil, and means for maintaining electrical connection between the terminals of said winding and said conductor element and shaft during relative motion between said tool shaft and said transformer.

6. Apparatus for heat treating a work piece by electro-magnetic induction comprising a stationary secondary transformer element having a hollow core, a work holder, a tool shaft extending through the hollow core and mounted for sliding movement therethrough, an induction head carried by said tool shaft for movement into and out of operative relation with a work piece held by said work holder, extensible circuit connections connecting the terminals of said induction head with the terminals of said secondary element, and a primary transformer element surrounding said secondary element.

'7. Apparatus for heat treating a work piece by electro-magnetic induction comprising a' stationary support, a transformer mounted on said support having a hollow core element and primary and secondary elements relatively movable into and out of coupled relation, a work holder mounted on said support for holding a work piece to be treated, a tool shaft mounted to slide through the hollow core of the transformer independently of said relative movement between the transformer elements, an induction head carried near one end of the tool shaft for movement into and out of cooperative heating relation with the work piece held by said holder, a heating coil carried by said induction head, said tool shaft including a pair of concentric, cylindrical, electrical conducting portions electrically connected with the terminals of the said heating coil, and a pair of contact-brush elements connecting the terminals of the transformer secondary element each with one of the said cylindrical conducting portions.

3, Apparatus for heat treating a work piece by electro-magnetic induction comprising a stationary support, a transformer mounted on said support having a hollow core element and primary and secondary elements relatively movable into and out of coupled relation, a work holder mounted on said support for holding a work piece to be treated, a tool shaft mounted to slide through the hollow core of the transfomer independently of said relative movement between the transformer elements, an induction head carried near one end of the tool shaft for movement into and out of cooperative heating relation with the work piece held by said holder, a heating coil carried by said induction head, said shaft including a pair of concentric, cylindrical, electrical conducting portions electrically connected with the terminals of the said heating coil, and a pair of contact-brush elements connecting the terminals of the transformer secondary element each with one of the said cylindrical conducting portions, together with means for imparting sliding motion to the shaft and means for imparting rotary motion to the shaft to effect sliding and rotary motion of the induction head relative to the work piece held in said holder.

the hollow core of the transformer independently of said relative movement between the transformer elements, an'induction head carried near one end of the tool shaft for movement into and out of cooperative heating relation with the work piece held by said holder, a heating coil carried by said induction head, said shaft including a pair of concentric, cylindrical, electrical conducting portions electrically connected with the terminals of the said heating coil, and a pair of contact-brush elements connecting the terminals of the transformer secondary element each with one of the said cylindrical'conducting portions, together with means for rotating the work holder relativeto the induction head.

10. Apparatus for heat treating a work piece by electro-magnetic induction comprising a sta-- tionary support, a transformer mounted on said support having a hollow core element and primary and secondary elements relatively movable into and out of coupled relation, a work holder mounted on said support for holding a work piece to be treated, a tool shaft mounted to slide through the hollow core of the transformer independently of said relative movement between the transformer elements, an induction head carried near the lower end of the tool shaft for movement into and out of cooperative heating relation with the work piece held by said holder, an energizing coil carried by said induction head, said shaft including a pair of concentric, cylindrical, electrical conducting portions electrically connected with the terminals of the said heating coil, and a pair of contact-brush elements connecting the terminals of the transformer secondary element each withone of the said cylindrical conducting portions, together with motor means for moving said shaft, and a separable joint in said shaft between the motor means and said contactbrushes for replacement of the parts carried by the shaft below the joint.

11. Apparatus for heat treating a work piece by electro-magnetic induction which comprises a hollow core power transformer, a tool shaft extending through the hollow core of the transformer and movable relative thereto, an induction heating coil carried by the tool shaft for movement relative to the work piece, said shaft including a pair of circuit conductor elements carried by the shaft and connected to the terminals of the coil, means for maintaining electrical connection from said circuit conductor elements to the secondary terminals of the transformer during relative motion between said tool shaft and the transformer, and a third, current transformer winding mounted within the hollow core of the transformer in inductive relation to the current path through the said means for maintaining electrical connection.

12. Apparatus as claimed in claim 11 in which the third, current transformer winding is arranged with its magnetic circuit and C111); ent circuit at substantially right angles to those of the power transformer.

13. Apparatus for heat treating a work piece by electro-magnetic induction comprising a support, a hollow magnetic core element mounted on said support, a secondary transformer winding on said core, a primary transformer element including a primary winding and outer cylindrical magnetic circuit element proportioned and arranged to slide over said hollow magnetic core and secondary winding into and out of inductive coupling therewith, motor means for moving said primary element into and out of coupling position, a tool shaft extending through said hollow core, an induction head carried by the shaft, motor means for moving the shaft axially relative to said core to move the induction head into and out of operative relation with a, work piece, circuit connections leading from the terminals of said secondary winding into the interior of the core to said shaft and circuit connections leading along said shaft to said induction head.

14. Apparatus for heat treating a work piece by electro-magnetic induction comprising a hollow core transformer, a tool shaft slidably extending through the hollow core of the transformer, means for effecting relative sliding movementbetween the tool shaft and the hollow core, an induction heating coil carried by said tool shaft, means for effecting relative movement between the heating coil and the work piece, said shaft including circuit conductor elements connected to the terminals of said coil, and means for maintaining electrical connection from said circuit conductor elements to the secondary terminals of the transformer during the relative movement between the said tool shaft and said transformer.

15. Apparatus for heat treating a work piece by 'electro-magnetic induction comprising a stationary support, a transformer mounted on said support having a hollow core element and primary and secondary elements relatively movable into and out of coupled relation, a work holder mounted on said support for holding a work piece to be treated, a tool shaft extending through the hollow core of the transformer, means for efl'ect ing relative sliding movement between the tool shaft and the hollow core independently of said relative movement between the transformer elements, an induction head carried near one end of the tool shaft, means for effecting relative movement between the'work holder and the tool shaft to move the induction head and the work piece held by said holder into and out of opera tive relation, a heating coil carried by said induction head, said shaft including a pair of concentric cylindrical conducting portions electrically connected with the terminals of the said heating coil and a pair of contact brush elements connecting the terminals of the transformer secondary element each with one of the said cylin drical conducting portions, together with means for eifecting relative motion between the tool shaft and the work holder.

16. Apparatus for heat treating a work piece by electro-magnetic induction comprising a stationary support, a transformer mounted on said support having primary and secondary elements relatively movable into and out of coupled rela tion, a work holder mounted on said support for holding a .work piece to be treated, a tool shaft slidably mounted with respect to said work hold er, an induction head carried near one end of the tool shaft, means for effecting relative movement between the work holder and the tool shaft to move the induction head and the work piece held by said holder into and out of operative relation, a heating energizing coil carried by said induction head, said shaft including p conducting portions electrically the terminals of the said heating of contact brush elements connecting nals of the transformer secondary ele with one of the said conducting 17. Apparatus for heat treating a 1 by electro-magnetic induction comps tionary support, a work holder for hol work piece slidably mounted on said so tool shaft slidably mounted on said sup fluid conduit carried by the shaft, an induct on head carried by said shaft, means for efiect lg relative movement between the shaft and work holder for bringing the induction. head a work piece held by said holder into opera relation, a tubular-conductor heating coil ca by said induction head, and a queue carried by the induction head having fluid cor-a nection with the said fluid conduit, one of said tubular-conductor coil communicat with the fluid conduit and the ct communicating with a space beyond on the side thereof away said i 18. An apparatus for progressively ii ing a workpiece by electromagnetic induc'tioi inducing coil, a support for said coil, means effecting relative longitudinal movement pet the workpiece to be heat-treated and port for progressively heating the work, ing side of said support being contours periphery to form one wall of a annular stream of quenching fluid ans. having a peripheral portion complement said wall to form the opposite wall of zle, at least one of said walls having a charnl therein in communication with said nozzle supply quenching fluid thereto.

19. An apparatus for progressively heat-ti ing a workpiece by electromagnetic induction, inducing'coil, a support; for said. coil, Eli effecting relative longitudinal movement the workpiece to be heat treated and i for progressively heating the work, the side of said support being contoured i. riphery to form one wall of a nozzle for c nular stream of quenching fluid niea ing a peripheral portion complementar wall to form the opposite wall f said last mentioned means havi ripheral portion contoured to for a second nozzle, said tary to said last mentioned Wall to positewall of said second nozzle.

20. An induction heat treating h gressively heat-treating an inner p wall of a cylindrical chem coil, a core of magnetic mate and having a portion extendin wardly across the trailing within close proximity to the treated, means for supporting a narrow circumferential flange j, said core portion and means and in association "with t flange to discharge quencin directly from the trailing s outwardly toward the Wall or" a direction axially fro the space axially beyond said axially spaced means.

21. Induction heat-treating apparatus for progressively. heat treating a surface portion of an elongated object, comprising an induction heat-,

element. and in a dire'ction axially away from said trailing edge the space between said heating element and the adjacent surface of the object being heated being in open communication with the space axially beyond the trailing end of said nozzle. l

22. An induction heat-treating head, comprising an annular induction heating element, means disposed within said element for supporting said element, said means having a quenching fluid passageway therein, and means secured to said supporting means having an annular quenching iluid discharge passage located adjacent one end of said heating element in axially spaced relation, said last-mentioned means having passage means therein for conducting quenching fluid from said passageway to said discharge passage.

23. In an induction heat-treating apparatus having a tool shaft and an induction heating coil carried thereby, means for reciprocating said tool shaft comprising a fixed annular cylinder surrounding haft in circumferentially spaced relation, the ends of said cylinder being in fluidsealed relatively slidable engagement with said shaft, a piston member within said cylinder and rigidly secured to said shaft, an inlet and outlet conduit for said cylinder for the admission and release of working fluid to and from the space in said cylinder between said piston and one end of said cylinder, means operable upon a predetermined position of said piston near said end of said cylinder for closing the communication between the interior of said cylinder and said conduit, and a by-pass passage means permanently connecting said space with said conduit.

24. In an induction heat-treating head, an induction heating element for inducing magnetic heating currents, means adjacent said head in axially spaced relation with respect to one end of said heating element for discharging quenching fluid, and a core of magnetic material for said heating element, said core having an extension extending between said quenching fluid discharging means and said end of said heating element for directing flux between said means and heating element and for shielding said means from the magnetic heating effect of said heating element.

25. An apparatus for progressively hardening the surface of a work piece comprising an induc ing head, a quench head adjacent the inducing head at least during the quenching operation, means for effecting relative movement between the work and said heads, means for rotating said quench head, means for supplying quenching fluid to said quench head during its rotation, said lastmentioned means including a rotatable pipe havquenching operation, means for effecting relative movement between the work and said heads, means for rotating said quench head,-means for supplying quenching fluid to said quench head during its rotation,- said last-mentioned means including a rotatable pipe having an opening through the wallthereof and having its interior in communication with said quench head, a stationary enclosure surrounding the portion of said pipe containing said opening, a quenching fluid supply passage connected to said enclosure, and means for imparting reciprocation to said pipe and quench head during its rotation.

27. In apparatus for heat treating a cylindrical work piece by electromagnetic induction, a frame member, a transformer element having a secondary winding and an annular core element for said winding carried by said frame member, an induction heating coil, an arbor comprising concentric conductor elements, one of said conductor elements supporting said coil, and said conductor elements being electrically connected withsaid coil and being coaxially arranged with respect to said core element,'means for moving said arbor relative to said core element, said conductor elements being insulated from each other, and means for maintaining electrical connections between said conductor elements and the termmals of said winding during movement of said arbor relative to said core element.

28. Apparatus for heat treating a cylindrical work piece by electromagnetic induction comprising a frame member, an electromagnetic inducing head mounted on said frame, a work holder support, means for movably mounting said support on said frame for movement axially of said head, a work holder, means for rotatably mounting said work holder on said support in coaxial alignment with said head, motor means for movmg said support to move the work carried by said holder into and out of o'perative heating relation with respect to said head, and motor means for rotating said work holder independently of the movement of said support.

v29. An induction heat treating head, comprising an induction heating element having a coolant passage therein provided with an inlet and an outlet, means disposed within said heating element in supporting relation and having a fluid passageway therein, and a quenching device secured to said means adjacent one end of said heating element and having a discharge nozzle opening, said coolant passage being in communication with both said inlet and said nozzle'opening for conducting fluid thereto, said means having a chamber for receiving fluid from said heating element and a passage for the flow of fluid therefrom.

HOWARD E. SOMES. 

